Process for the continuous recovery of glycering from soap



Nov. 7, 1939.

B. H. THURMAN 2.179.001

PROCESS FOR THE CONTINUOUS RECOVERY OF GLYCERINE FROM SOAP Filed June 14, 1937 flea/4111121 [hr 2am mus-.1 Nov. 1, 1939 rnocnss non. m coiv'rnvoofis uncovsit! or sarcasm mom soar Benjamin H. Thurman, Bronxville, N. Y., assignor to Refining, Inc., Reno, Nev., a corporation oi Nevada Applicatign June 14, 1 31, Serial No. 148,240 11 Claims. (c1. zoo-41s) This invention relates to a process for the treatment of soap and more particularly to a process in which a mass of soap made in a kettle, or otherwise,'is processed to remove volatiles therefrom.

In the commercial manufacture of soap a mixture of soap and water is produced. Ii glycerides are employed as the saponiflable material, this mixture also contains glycerin. The removal and recovery of the glycerin from soap mixtures, as heretofore practiced, is more diflicult and time consuming than the original preparation of the soap mixture. In prior processes, a strong salt solution is added to the mixture in order to throw .15 the soap out of the solution while at thesame time dissolving the glycerin. Then, after the salted mixture has been boiled for a considerable time, it is allowed to. settle for several hours. The soap lye which separates contains much oi the glycerin but a portion remains associated with the soap. To further purity the soap and remove additional glycerin therefrom, it is necessary to repeatedly subject the soap to washing or salting out operations.

Also the recovery of the glycerin from the soap lye from prior process requires a long andcomplex process. It usually involves chemical treatment followed by evaporation of water, resulting in an appreciable loss of glycerin. 'I'he crude ao glycerin thereby obtained has to be iui'tlier treated by distillation and other processes, resulting in additional loss of glycerin, before a commercially pure glycerin is obtained.

-' The soap mass after the glycerin has been with:

as drawn therefrom is then treated to remove moisture if a solid or powdered soap isobtained. The variousprocesses of removing this moisture are also expensive and time consuming. The presentinvention eliminates'all oi these difllcult'ies and 40 rapidly produces extremely pure glycerin and soap in marketable form. I In accordance with the present invention, the glycerin and water are removed "from a soap mixture by vaporizing the same and the soap can be 45 recovered in substantially anhydrous and glycerin-iree form. This process of separating glycerin from the soap is continuous and large quantities may be treated in a relatively short time.

It is, therefore, an object of the invention to to provide an improved process oi separating volatiles from soap mixtures such as are produced in the manufacture of soap. j

, Another object of the inventionis to provide a continuous process of recovering glycerin oi as high purity from soap In addition the soap mixture can by the pres ent process be subjected to temperatures and pressures far in excess of those possible in theconventional methods of processing soap mix tures even if no glycerin is present or it is not 5 desired to recover the same. By such high temperatures various colored and odorous impurities contained in many soap making materials, for example, higher alcohols such as .sterols, may be vaporized and the vapors separated from the soap in in an evaporating zone thus producing a purer soap. Also many insoluble impurities which ordinarily color the soap or later break down to give the soapan undesirable odor, for example, insoluble proteinaceous materials, are broken down by ii?- the high temperatures, capable of being employed in the present'process, into non-odorous or colorless compounds or rendered vaporizable or soluble so that they may be removed by evaporation or washed out of the resultant soap. Thus very low t; grade soap mixtures, such as cottonseed or other soapstock resulting from refining operations or soap mixtures made from low grade fats, can be treated by the present process to produce much lightercolored and better grades of soap than can 25 ',be made by conventional processes. The high temperature treating step may be of such short duration that the soap is not injuredeven though prolonged treatment oi the soap at the high temperature would decompose the same.

It is, therefore, another object of the invention' to subject a soap mixture to high temperatures in order to vaporize or break down colored and odorous impurities.

A still further and quite important object of my invention is to provide a process wherein saponiflcation may be effected in a kettle, for example, under relatively low temperatures and for a relatively long period of time after which the resulting mixture, including soap, glycerin and m water is continuously and quick y Passed through a heating zone where it is subjected to an elevated temperature for a short period of time before continuously discharging it into a vacuum chamber where the glycerin, water and other materials are ,vaporized thereirom'and separately condensed while the soap is discharged fromthe vacuum without breaking the same.

Still more specifically, thev invention c'ompree .hends the employment of a pumping mechanism 0 interposed between the relatively large kettle containing the saponified or partially .saponifled product and the coil, constituting the heating" zone, for performing the dual function .of forcing the saponifled mixture through the coil at a a substantial rate of flow to maintain the mixture while it is subjected to high temperatures and of more thoroughly mixing the saponified material, thereby providing for contact between any unsaponified material and saponifying agent to further the saponiilcation before the mixture reaches the high temperature zone.

Other objects and advantages of the invention will appear in the following description of the preferred embodiments of the invention which are described in connection with a schematic drawing of a suitable apparatus, of which:

Figure 1 is an assembly view of the entire apparatus, and;

Figure 2 is a fragmentary view in section showing an arrangement of nozzles in the evaporating chamber.

Referring to the drawing, HI indicates, in general, apparatus suitable for carrying on a saponification step; ii indicates a heating device for heating a soap mixture; I2 indicates in general an evaporating chamber which is provided with a conveyor system indicated at i3 for removing soap from the evaporating chamber; and l 4 indicates a condensing system for condensing glycerin and water vapors.

The apparatus ill for making soap mixture may include conventional soap kettles i5 and i6, provided with heating jackets I! through which steam or other heating medium may be passed by the pipe l3. Pipes l9 and 20 are provided for introducing a measured quantity of a saponiflable material-and a saponifying reagent, respectively. These materials are mixed in the kettle by an agitator 2i driven by a motor 22 while the materials are heated by the steam jacket H. The saponifying reagent, which is usually a caustic alkali, reacts with the saponiflable material to form a soap mixture. Duplicate kettles will ordinarily be provided so that soap can be made in one kettle while the soap mixture is being withdrawn from the other and processed. Instead of making the soap mixture in the kettles illustrated, it may be produced in other apparatus and delivered to the kettles from which it is supplied to the remainder of the process.

For withdrawing the soap from either kettle, pipes 23 and 24 leading from the bottoms of the kettles are provided and are connected to a pipe 25 leading to a pump 23. Valves 2'! and 23 are positioned in the pipes 23 and 24, respectively, in

order to provide forwithdrawing soap from either kettle. Also a pipe 23 connected to pipes 23 and 24 through valves 33 and 3| may be employed for diverting portions of the soap mixture to other processes or for cleaning purposes. The soap mixture in the kettles should be maintained in substantially uniform admixture during withdrawal of the same as, for example, by the agitators 2| or by passing steam through the mixture, and should be rendered sumciently fluid to enable it to be pumped through the process by heating or dilution.

Pump 23 may be any type of pump suitable for forcing the soap mixture under a relatively high pressure through a heating coil 32 positioned in a casing 33 forming part of the heating device I I. Heat may be applied to the suitable means, for example, by .a the lower portion of the casing 33. order to control the amount of heat applied to the coil a suitable thermostatic device 35 may be employed for controlling the amount of fuel delivered to the burner 34. Such a device may include a member 33 into which the heated mm ill coilbyany' burner-34in the coil 3. are delivered by the tube 31 so that these materials flow in contact with the walls of the member 35 and are discharged through a pipe 33. In the device shown, the products of combustion from the burner 34 also contact the member 35 so that the temperature of this member is determined by both the temperature of the materials discharged from the coil 32 and that of the products of combustion. A valve 39 is connected to one end of the member 36 so that expansion due to increase in temperature of this member partially closes the valve to reduce the flow of fuel to burner 34. Likewise a decrease in temperature of the member 35 increases the flow of fuel to burner 34. The normal position of the valve 33 can be controlled by a hand-wheel 40 mounted upon shaft 4| rotatively attached to one end of the member 35 and screw-threaded through a member 42 attached to the casing 33. By adjusting the hand-wheel 40, any desired temperature of the materials discharging from the coil 32 can be automatically maintained.

Any desired pressure may be imposed upon a mixture in the coil 32 by the pump 26 and this pressure may be maintained by valve 43 in the pipe 33 or by a restricted discharge orifice in the nozzles 44 positioned in the'evaporating chamber l2. Alternatively, if desired, the diameter of the tube forming the coil 32 may be made sufilciently small to maintain the desired pressure.

If glycerin is to be recovered, the soap mixture is heated in the coil 32 to a suflicient temperature to cause the glycerin thereof to be vaporized when discharged into the evaporating chamber l2 and is maintained out of contact with the atmosphere in its heated state. As herein after explained, the pressure and temperature in the coil 32 may be regulated, if desired, so that water or glycerin vapors are generated in the coil 32. The pressure at the discharge end of the coil will depend upon the temperature employed so as to secure the desired amount of vaporization in the coil.

The evaporating chamber may include an inner casing 45 closed to the atmosphere and having a heating jacket 46 positioned therearound. Steam or other heating medium may be admitted to the heating jacket 45 through a pipe 41 and the heating jacket is preferably surrounded by an insulating covering 43. It has been found advantageous to direct the mixture discharge from the nozzles 44 against the heated walls of the evaporating chamber so that the mixture flows down these walls in a relatively thin him and the glycerin and water vapors are more easily liberated. A preferred arrangement oi the nozzles 44 to accomplish this purpose is shown in Fig. 2. It will be noted that the liberated vapors are not required to pass through a spray of material delivered into the evaporating'chamber to reach the vapor pipe 49 but have a substantially unimpeded path upwardly through the central portion of the chamber. By jhis arrangement entrainment of liquid or solid: materials in the vapors leaving the! evaporating chamber is substantially eliminated. The vapors present in the evaporating chamber are withdrawn through the pipe 43 and entrainment separator 43' to a condenser "provided with a receiver 5|. The entrainment separater 43' ranoves any tracesof solid or liquids in the vapors and returns them through a pipe 53' to the evaporating chamlpr. The entrainment separatoris preferably provided with a heating Jacket II to prevent condensation of glycerin (therein. In the condenser ll most of the glycerin g heating or coolingmedlur'n' to be introduced vapors are.condensed and glycerin flows into the receiver I while the water vapors are withdrawn from the receiver 5| through a pipe 52 to a water condenser 53 in which they are condensed and the resulting water flows into a receiver 54. A vacuum pump 85 withdraws uncondensed vapors from the receiver 54 and maintains a vacuum throughout the condensing system I4 and evaporating chamber 4!. Suitable cooling means (not shown) may be provided for the condensers and 53 and the temperature therein controlled so that fractional condensation of the water and glycerin takes place. A fractionation column may be employed instead of separate condensers, if

desired. The condensate from the various receivers may be removed through the pipes 56 and 51,.for example, by pumps (not shown). A small portion of glycerin ordinarily is found admixed with the water in receiverbl and this water may be employed as part of the water in the saponiilcation step so that the glycerin is subsequently recovered in the process. A. greater number of' condensers may be provided if a greater number of condensate fractions are desired.

The heating jacket 46 around the evaporating chamber 45 supplies additional heat for vaporizing glycerin and in some instances it is desirable to furnish still more heat by injecting steam, preferably superheated, into the evaporating chamber by a pipe 60. This steam also has a further function of assisting in liberating the glycerin vapors from the soap and carrying them to the condensing system H.

In order to remove substantially all of the glycerin from the soap, the temperature in the evaporating chamber 45 must usually be suflicient to'cause the soap to be in a molten or plastic condition, although the soap may deposit in the bottom of the evaporating chamber in a powdered form with certain types of fat, particularly if the conditions are such that all of the glycerin is not vaporized. However, if glycerinis to be evaporated, the soap collecting in the bottom of the chamber 45 is at a temperature such that contact with the atmosphere will cause deterioration. Y The soap must be promptly reheating medium may be passed through-the moved from the evaporating chamber as the temperature therein is sufficient to cause deterioration of the soap if it is maintained at this temperature for a prolonged length of time. It is, therefore, necessary to promptly remove the soap and cool the same before it is allowed to .come

in contact with the atmosphere.

A suitable apparatus for-this purpose is the conveyor system i3. This system may include a screw conveyor. 8| having a casing 62 opening into the bottom of the evaporating chamber 45.

The inclined walls 83 of this chamber direct the soap'into the conveyor casing. 52. Jackets 64 and 65 surround the conveyor casing 62 for heating or cooling the same. Either a cooling medium or jacket (depending upon the temperature of the soap-in the conveyor. It is necessary that the soap be suiiiciently solid before leaving the conveyor system that it effectively plugs the discharge from the conveyor and in some cases this may require cooling by the jacket 85, although ordinarily a heating medium will be passed through this Jacket in' order to help maintain the temperature in the evaporating chamber 45. A cooling medium is passedthrough the jacket 64 in order to'cool the soap. Also the conveyor shaft 66 may bemade hollow and may be provided with an inner pipe 61 so as to enable a the mixture substantially uniio through the,pipe 61 and discharged through the pipe 88 connected to the pipe 61 through a suitable packing gland 88'. This last means provides an extremely sensitive device for controlling the temperature of the soap being discharged by the conveyor Bl. the soap to be discharged by the conveyor 6|, stationary members 6.9 extending through the conveyor casing may be provided to prevent the soap mass from turning with the conveyor. Slots 10 are provided in the screw portion of the con- In order to assist in causing veyor to receive the members 69. It has been found advantageous to enlarge the conveyor shaft adjacent the discharge end as at 69', in order to provide a tapered and restricted discharge passage to assist in causing the soap mass to seal the conveyor against entrance of air to maintain the veyor casing 62 by a vent 12,. preferably leadingto the vapor pipe 49.

Preferably theconveyor 6| discharges into a second conveyor 13 positioned at right angles thereto and provided with a cooling jacket 14 although a single conveyor may, in some instances, be suflicient. This conveyor may be of the same type 'as conveyor SI and discharges through a valve 15. to the atmosphere. This valve is employed in starting up the apparatus in order to maintain a vacuum in the chamber 45 before the conveyor system becomes filled withsoap. The conveyor shafts are rotated by means of the sprockets 16 and are provided with bearings 11' adjacent the sprockets, but no bearings need be employed at the discharge end of the conveyors.

A pipe 11', leading into the inlet end of the second conveyor 14 may be provided for the introduction of other materials into this conveyor for admixture with the, soap therein. The conveyor screw moves the soap away from this portion of the conveyor so that a .low pressure space is provided for the introduction of materials. water for rehydrating the soap to any desired 'extent or perfume or soap builders or fillers may be introduced and mixed with the soap. I 7

In carrying out the process of the present in- Thus vention a batch of-ssoap isv made in one of the kettles I! or it or other suitable apparatus d delivered by the pump ZG -to the heating de e ll. Thetemperature during saponiflcation an the proportions of-materials usedi may be tho known to the prior art. Thus, temperatures 1 the order of to 212 F. may be employed or even higher temperatures up to, for example, 450 R, if closed receptacles are provided so that saponiflcation is under pressure. may be employed in the saponification step without danger of injuring the soap or soap making materials.

The agitation should be continued during with-- drawal of the soap mixture in orderto maintain The pump 28 not only provides pressure or ,Lfgrcing the materials through the heating device, and into the evaporating chamber 45 but also aids in fur ther mixing the materials passed thereth'rough.

The coil 32 has been found to provide emcient heating without local overheating, but any other type of heating device in which the materials can be heated to a high temperature and under pressure without local overheating may be employed. Also the thermostatic device 35 performs a further mixing function immediately before the materials are delivered into the evaporating chamber 15, although any other type of mixing device may be substituted therefor and in many instances such mixing necessary. The temperature to which the materials are raised in the heating device will depend upon the type of glyceride or fat being treated, and in general these temperatures will be between 450 and 620 F. As has been indicated before, it is generally necessary to have the soap deposited in the evaporating chamber in a molten or plastic condition in order to satisfactorily recover the glycerin, and for this purpose the temperature of the mixture introduced into the evaporating chamber should be suiliciently high to produce such molten or plastic soap. Even if glycerin is not present or is not recovered, it may be desirable to employ temperatures in the upper portion of the above range in order to vaporize or break 'down impurities in the soap. It is important that the material subjected to the higher temperatures be substantially completely saponified as such temperatures. in many cases, tend to discolor glycerides and fatty acids.

In many cases, soap mixtures from commercial soap making processes may contain unsaponified fatty acids or glycerides occluded in soap masses or particles and these may even be present in the finished soap from Prior processes. The present invention is particularly adapted for handling such soap mixtures since the rapid flow through at least the first part of the heating zone along with the passage of the material through the soap pump and connecting pipes breaks down any agglomerations of soap and unsaponified material and enables the unsaponified material to be substantially completely sapon fled. Even in cases where fatty acids are employed as the saponifiable material so that no glycerin is present in the soap mixture or it is desired to leave glycerin in the treated soap, a higher tem perature is employed in the heating zone than in the saponification step. This temthat use perature must be'suflicieni. to rapidly vaporize the wat r either in the heating zone or in the evaporating chamber and the present process provides forrapidly heating the soap mixture to this temperature so that the soap mixture is not subjected to the higher temperature for prolonged periods of time. Thus the saponification step may be carried on by heating to relatively low temperatures over considerable periods of time so as to obtain substantial saponification without danger of injuring the .soap or saponifiable material by high temperatures. The temperature may then be rapidly raised in the heating zone and the volatiles promptly removed so that the soap mixtures are subjected to the higher temperature for a brief period as compared to the time of treatment in the saponification step. A

period of 2 to 5 minutes is usually sumcient for the entire heating step. The temperatures necessary to vaporize the water do, however, accelerate the saponification reaction and even the short period of treatment at the higher temperatures, accompanied by rapid flow of the soap mixture, substantially completes the saponification of the unsaponified materials. Because of has been found to be unhowever, the first they rapid saponification in the heating zone, partial saponification only may be accomplished in the prior saponincation step and excellent results obtained by completing the saponiflcation in the heating step. If unsaponified fatty acids or glycerides are present at the highest temperature in the heating zone, this temperature should not be above the "flash point" of the unsaponifled materials.

When the temperature is raised above this flash point, as is usually necessary to vaporize glycerin, care should be taken that saponification is substantially complete before this temperature is reached, since such temperatures are likely to discolor unsaponified fatty acids or glycerides as above indicated. Even in this case, or lower temperature portion of the heating zone may be employed to complete the saponification of unsaponified material since the temperature progressively increases during the passage of the mixture through the heating zone and the saponification reaction proceeds very rapidly as the temperature increases especially if the material being heated has been more thoroughly mixed by passage through the soap pump and connecting pipes.

The invention therefore provides an extremely inexpensive and quick process. Moreover, by reason of the rapidity of fiow of the partially or wholly saponified mixture through the coil 32, a

high temperature may be imposed thereon sutlicient to flash oil. not only the glycerin and water but other impurities as well, without detrimentaily affecting the soap because of its momentary exposure to the elevated heat treatment and the fact that saponification has proceeded under relatively low temperatures and for a relatively long period of time in the kettle or other receptacle H.

An important advantage of the present invention is that various types of volatile saponification accelerators, for example, beta naphthol, can be employed in the saponiflcation step even though they are undesirable in the finished soap. Such volatile accelerators can be substantially completely removed from the soap in the evaporating step after they have performed their function of decreasing the time necessary for the saponification step. 0n the other hand certain non-volatile saponification accelerators have valuable anti-oxidant properties in the finished soap and can be retained therein by the present proc- -ess even though they are water soluble and would be to a large extent removed by the washing or glycerin removal steps of conventional processes. In either case, in addition to shortening the time necessary for the saponification step, the accelerator assists in substantially completely saponifyingthe saponifiable materialbefore high temperatures which would injure the same are reached.

The pressure imposed by the pump 26 must be sufiicient to allow the desired temperature to be attained. In actual operations for the recovery of glycerin, the temperatures and pressures are ordinarily controlled so that water vapors and preferably some glycerin vapors are formed in the heating device II at the pressure therein. Usually it is found desirable to thus vaporize substantially all of the water. Such operation permits more heat to be imparted to the mixture and requires less vaporization with consequent absorption of heat in the evaporating chamber 45. Sufficient heat must be supplied to the evaporating chamber either from the heating device H or by other means to maintain a va- 7| porizing temperature for the glycerin therein. By forming at least part-of the vapors in the heating device 32, less additional heat is required to be delivered to the evaporating chamber 45, although in many cases, it is possible to carry on the present process without forming vapors in the heating device 32.

The temperature of the soap deposit" in the evaporating chamber will depend upon the amount of glycerin to be recovered therefrom and the nature of the saponifiabl'e material being treated. Certain soaps, for example, those from the lighter fatty acids, will be'molten at 455 F., while others require temperatures as high as 565 F. In order to vaporize the glycerin in the evaporating chamber it is preferable that as near a perfect vacuum as possible be maintained in the evaporating chamber and that heat be supplied to the evaporating chamber either by means of a heating jacket 46 or by superheating steam through the pipe 60. Both of these expedients may also be employed.

'Ihus the present invention provides'an improved process which eliminates the expensive and time consuming process of removing volatiles from soap made by conventional processes. The saponifying reaction should be substantially complete before the materials are heated to a glycerin vaporizing temperature in order to prevent possible discoloration of the fatty acids or glycerides.

' Glycerin can be recovered in a relatively pure and concentrated form and substantially all of the glycerin can be obtained. Also, the soap may be produced in a commercially usable form subbodimefit of'my invention, it is understood that I am not to be limited to the details thereof and of the fo owing claims.

i What claim is: a

1. A method of making soap by the reaction between a saponifiable material and a saponifythat the ifivention may be varied within the scope ing material, which method includes the steps of saponifying a mixture of said materials under heat while maintaining the temperature below that value at which discoloration due to traces of unreacted saponifiable material will result,

thus producing a soap mixture containing soap,

glycerin and traces of unreacted saponiflable material; then processing said soap mixture to saponify said traces of unreacted saponinable material to produce a completely saponifled soap product still containing glycerin; then heating said soap product to a higher temperature and subjecting same to a vacuum, the heating being suflicient to cause vaporation oi glycerin under said vacuum conditions; separating glycerin vapor from the soap while maintaining the soap in molten, plastic or semi-plastic condition while subjected to said vacuum conditions and promptly, substantially as soon as the soaphas been deposited in said vacuum, removing the same without impairing the vacuum.

2. A method of making soap by the reaction between a saponiflable material and a saponiiying material, which method includes the steps of saponifying a mixture 01 said materials under heat while maintaining the temperature below that value at which discolorization due to traces of unreacted saponifiable material will result, thus producing a soap mixture containing soap, glycerin and traces of unreacted saponiflable material; then continuously moving a stream of said soap mixture into and through a mixing zone and subjecting same. to a-mixing actionwhile therein to produce a completely saponified soamproduct still containing glycerin; then subjecting said completely saponified product to higher temperature and moving same into achamber maintained under vacuum, the temperature of said soap product being raised to such an extent that glycerin vapors will separate at the low pressure maintained in said chamber;

continuously removing the separated vapor from said chamber at such rate as to maintain the vacuum therein and removing said soap from said chamber substantially as quickly as the same is deposited therein and before injury thereto.

3. A process for making soap and separating glycerin which comprises the'steps of: mixing saponifiable glycerides with a saponifying *reagent in a saponification zone to eifect substantial saponification such that heating of the resulting mixture comprising soap, water and glycerin will produce substantially complete saponiflcation before the temperature of the mixture reaches that at which glycerin will separate in vapor form when discharged into a vapor separating zone, maintaining a relatively low temperature during said saponiflcation in said saponification zone insuiiicient to render the soap molten when anhydrous whereby discoloration due to traces of unsaponified saponifiable material is prevented, withdrawing a stream of said mixture from the saponification zone and rapidly advancing the same under pressure through a separate heating conduit, drastically heating the mixture during its rapid and turbulent flow through said conduit to a'temperature greatly in excess of that maintained in the saponiflcation zone and sufllcient to separate said glycerin and other impurities when introduced to a vapor separating zone, continuously discharging the mixture into a vapor separating zone while maintaining a temperature suillcient to render the resulting anhydrous soap in a molten condition, continuously withdrawing the glycerin vapors at a rate sumcient to maintain a vacuum therein and continuously removing the anhydrous molten soap from said chamber without impairing said vacu 4) A rocess for making soap and separating glyce which comprises the steps of: mixing saponiflable glycerides with a s'aponifying reagent in a saponifying kettle to effect substantially saponification such that heating of the .resulting mixture comprising soap, water and glycerin will produce substantially complete saponiflcation before the temperature of the mixture reaches that at'which glycerin will separate in vapor form when discharged into a vapor separating zone, maintaining a relatively low temperature during the saponiflcation in said kettle, insuflicient to render the soap molten when anhydrous, withdrawing a small stream of said 'mixture from the saponification kettle and rapid ly advancing the same, under pressure, through a separate heating conduit, abruptly elevating the temperature imposed upon the previously sapont- 75 limited to such a few minutes as to prevent injury to the soap.

6.111eprocessasdefinedinc1aim4inwhich the relatively low temperature and pressure conditions maintained in the kettle during saponification are insufficient to vaporize the glycerin whereby to prevent discoloration of the soap and wherein the temperature abruptly imposed upon theheatingconduitisnotsubstantiallylessthan' 7.Aprocessformaking pandremoving vaporizable which comprises the steps of: admixing saponiflable and saponifying materialsinasaponificationzonetoproduceamixture of soap and vaporizable impurities; maintainin a temperatureand pressure during said saponifieation insuflieient to vaporize said impurities whereby to streamingsaidmixturethroughaseparateand independent heating conduit; vaporizing the unsaponifiable impurities contained in said presaponified mixture by abruptly and drasapplying a temperature in excess of that maintained in the saponiiication step and sumcieuttorenderthe resultantanhydromsoapina molten limiting the duration of the drastic heating step for a relatively brief period,

Ywusly finally anddischargmgthemixtureintoavaporsepa-.

heating of the resulting kettle soap containing glycerin will produce substantially complete saponincaticn before the temperature of the kettle soap reaches that at which glycerin will separate in vapor form when discharged into a vapor separating zone, thereafter pumping a stream of said kettle soap through a heating zone to rapidly heat the same to a temperature shillciently high to cause substantially all of said glycerin to be separated in vapor form when said stream is introduced into a vapor separating zone and above the melting point of the soap when said glycerin has been separated, introducing the heated stream into a vapor separating chamber maintained under vacuum, continuously withdrawing glycerin vapors, and promptly and continuously withdrawing purified soap from said chamber before the same is damaged by high temperatures and while scaling said chamber from the atmosphere.

10. The process of making soap and rapidly separating glycerin therefrom which comprises:

a saponification reagent with a glyceride of a fatty acid in proper proportion, substantially completely saponifying said glyceride at a temperature below the vaporization point of glycerin and below the point at which discoloration due to traces of unsaponified saponifiable material will result, thereafter rapidly heating a stream of the substantially completely reacted mixture out of contact with the air to a temperature which will cause glycerin to be separated in vapor form when said mixture is introduced into a vapor separating zone maintained under vacuum, introducing the heated stream into said vapor separation zone whereby said glycerin is substantially immediately separated in vapor form and anhydrous substantially glycerin free soap is deposited in said chamber, withdrawing vapors at a rate which will maintain said vacuum, and rapidly withdrawing said soap before the same has been damaged by said glycerin separating temperature.

11. A two-stage process for making soap which comprises the steps of: mixing a saponification reagent with a glyceride of a fatty acid in proper proportions, substantially completely saponifying said glyceride at a temperature below the vaporization point of glycerin and below the point at which discoloration due to traces of unsaponified material will result, thereafter elevating the temperature of the mixture to a degree which will cause glycerin to be separated in vapor form when said mixture is introduced into a vapor separating zone, introducing the heated stream into said vapor separation zone whereby said glycerin is substantiallyimmediately separated in vapor form and anhydrous substantially glycerin 'free soap is deposited in said chamber, withdrawing said vapors from said zone and rapidly withdrawing said anhydrous soap substantially as quickly as the same is deposited in said zone and before the same has been damaged bysaid glycerin separating temperature.

BENJAMIN H. THURMAN. 

